I have an Ipad mini 6 and an Iphone SE (2022): can I use the adapters they came with to recharge in Japan for when I travel there??

all apples psus and ac chargers works from 100volt to 240volt AC

you may need a plug converter depending on how the plugs look in your country vs. how they look in japan

you can charge the iphone with the ipads ac charger but if the iphone have a 5watt ac charger it will not be enough for the ipad to charge